Technical Abstract:
Phakopsora pachyrhizi Sydow is the causal agent of Asian soybean rust (ASR), one of the most destructive diseases of soybean (Glycine max (L.) Merr.). Before 2004, ASR was not present in the continental USA and evaluation of U.S. soybean lines for resistance was conducted only with foreign isolates. Since ASR has been discovered in North America, evaluation of soybean lines using U.S. isolates is important in order to identify new resistance sources. In this study, 10 plant introductions (PI) previously identified as resistant in Paraguay were evaluated using an ASR isolate from Mississippi. Replicated experiments were conducted in a growth chamber at the Stoneville Research Quarantine Facility from 2006 to 2007. Soybean line PI567102B was identified as the most resistant line. It had the lowest severity, no sporulation, and the red-brown reaction. Further evaluation using other U.S. isolates is in progress. Collaborative research with other scientists will be conducted to evaluate the segregation of a population with PI567102B as a parent for genetics study. Soybean lines having resistant reactions to both U.S. and Paraguay isolates may be important for developing elite cultivars with broad resistance to ASR.